Method of determining proportions in compositions of substances



Dec. 19,- 1950 G HERZOG 2,534,352

METHOD OF DE'IIERMINING PROPORTIONS IN COMPOSITIONS OF' SUBSTANCESTlcyl.

Filed Jan. 25. 1945 'T1 :I -l 24A f8 maar/wf- ENE Patented Dec. 19, T950METHOD OF DETERMINING PROPORTIONS IN COMPOSITIONS OF SUBS'llANCESlGerhard Herzog, Houston, Tex., assigner to The Texas Company, New York,N. Y., a corporation of Delaware Application January 23, 1945, SerialNo. 574,135

4 Claims.

This invention relates to a method of measuring or controlling theproportions or ratio of two substances in a composition of thosesubstances and it is the principal object of the invention to provide amethod of this kind by means of which accurate determinations can bemade of the proportions of two substances in a composition regardless ofthe form of the composition, i. e., regardless of whether it is amixture, a solution, emulsion, suspension or a chemical combination andwithout the necessity of any deformation of the composition, if a solid,and without access to the interior of the vessel or pipe containing thecomposition, if in the form of a fluid.

Many difficulties are encountered in connection with the determinationor measurement of the proportions of two substances in a compositionwhere access is not readily obtainable to the interior of the vessel orpipe holding the composition. Again, where the composition is in theform of, say, a sample of a solid it is very difficult to determine theproportions of the constituents without removing a portion of the sampleor otherwise disguring or deforming the sample in order to make theanalysis. As an example, let us assume that a composition is formed oftwo substances either in a homogeneous or a non-homogenous mixture andin the form of, say, a block or a brick. Without removing av portion ofthe block for chemical analysis, it would obviously be diicult todetermine the proportions of the two substances. As another example,suppose that a iiuid is ilowing through a pipe and that the fluid isformed of two substances the ratio of which it is desired to ascertain.Without removing a sample of the iiowing fluid for analysis by weighingor by chemical means, it would obviously be difficult to determine theexact ratio of the two substances forming the fluid. It would be stillmore difficult to make a continuous record showing substantiallyinstantaneously variations in the ratio of the two fluids withoutcontinuously removing or by-passing a small amount of the uid to be usedfor analysis.

In accordance with the present invention a method has been devisedthrough the use of which the desired results mentioned above, i. e.,measurement or control of the proportions of substances in acomposition, can be obtained, and this regardless of the form of thecomposition, i. e., whether it is a solidor a fluid mixture, a solution,emulsion, suspension or a chemical combination. Through the use of theinvention it is also- :Huid owing through a pipe, without removing' l 2samples and without any access to the interior of the pipe for theinsertion of thermocouple elements, or the like.

In carrying out the invention, a beam of penetrative radiation istransmitted through the composition, the proportions of which it isdesired to ascertain and a measurement is made of the intensity of theradiation after it has traversed the composition. The length of the pathof the beam through the composition may be selected so that apredetermined accuracy can be obtained. Thus, the beam may passdiagonally through a pipe carrying a iluid composition or it may passthrough a selected portion of a vessel in which the composition is beingtreated. By proper calibration of the measuring instrument, theintensity reading can be made to indicate directly the ratio of the twosubstances in the composition being examined. For calibration purposes ameasurement as described abovecan be made where the beam of radiation istransmitted through each of the substances separately providing that thelength of the path of the beam through the substances is the same as inthe case where the beam is transmitted through the mixture orcomposition. If desired, instead of measuring the intensity of theradiation passing through each of the substances taken alone,measurements can be made through known mixtures, i. e., compositionswherein the proportions or the ratio of the two substances are known,and a calibration curve then prepared from which the ratio of thesubstances in an unknown composition can subsequently be read directly.

As an example of an application of the invention a description will begiven of the use of the method as applied in determining the ratio ofacid catalyst to hydrocarbons in an alkylation process whereinisoparaflinic hydrocarbons are alkylated to produce hydrocarbonssuitable for an aviation type motor fuel.

For a better understanding of the invention reference may be had to theaccompanying drawing in which Fig. 1 is a somewhat diagrammaticillustration through a vessel containing a composition of two substancesthe ratio of which it is desired to ascertain,

' Fig. 2 is a vertical elevation showing apparatus used in an alkylationprocess,

Fig. 3 is a diagram to which reference will be made in explaining theprinciples of the inven tion,

Fig. 4 is an enlargedview through a section of pipe showing a somewhatdifferent arrangement ofthe radiation source and detector, while Fig. 5is a sectional plan view through a vessel showing an arrangement ofapparatus for controlling the proportions of substances of a compositionwithin the Vessel.

In Figure 1 of the drawing a vessel lil is shown as containing aquantity of a composition l2 which maybe a mixture of two substances oran emulsion, solution or chemical composition of the two substances. Ahousing or block i4 of a material such as lead capable of absorbinggamma radiation contains at its inner surfacea small amount of aradioactive substance I6, such as radium, and a beam of the penetrativeradiation, indicated diagrammatically by the dotted line 22, istransmitted through the walls of the vessel l!) and through thecomposition l2. At another side of the vessel Il! is a housing 24containing a suitable detector 28 of penetrative radiation which maycomprise a Geiger-Muller counter, a proportional counter or anionization chamber. The detector 26 is connected to a suitable amplier28, the output of which is inY turn led to a measuring instrument suchas the meter 30. If desired, a suitable preamplifier may be disposedwithin the housing 24.

With reference to 4Figure 3 let us assume that the side walls of theVessel l0 of Figure 1 are denoted by the vertical lines I0 and thatthese walls have no appreciable thickness; that the intensity oi theincoming radiation beam is indicated at I0 and that the rintensity ofthe radiation emerging from the vessel is indicated by I. Also let usassume that there are'two substances a and b in the vessel and theycross-hatched portions indicate the relative Aproportions of these twosubstances in the path of the beam of transmitted radiation. Forpurposes of illustration only, the amount of the substance a isindicated by the block or section markeda as though this substance wereall in one place, likewise that the substance b is positioned in oneplace in alignment with the radiation -source and the substance a. Thenthe distance will designate the proportion of the substance a in themixture or composition and 1 minus designates the portion of thesubstance b, 1, of course, indicating the length of the path of the beamthrough the composition.

First let us assume that there is only one substance in the vessell I9and that the beam of radiation therefore passes through nothing otherthan this substance a and the walls of the vessel. Then,

a :IOekl 1 where Ia is the intensity of .the radiation which has passedthrough the substance a, and ka is the absorption coefficient for thesubstance a.

Assuming then that Ythe substance b is the only substance in the pathoiv the beam of radiation,

where kb is the absorption coefficient for the substance b.

Let us assume now that both substances are in the Vesselras shown inFigure 3 and that I is the intensity of the radiation after it haspassed through the substance a and before it reaches the substance b,then From Equations 1, 2 and 5 one can solve for the three unknowns ka,kb and r. If 1 is assumed to be one then a: will be the percentage ofthe substance a in the composition ab. In this discussion we haveassumed that the walls have no thickness. In an actual case where thecomposition is in a container, the equations would obviously include afactor to represent the absorbing effect of the walls.

It is to be understood that the substances a and b within the path ofthe radiation beam can be mixed in any manner or they can comprise asolution, an emulsion or dispersion, or a chemical combination of thetwo substances since the absorption of the radiation in the compositiondepends only upon the atomic structure. In other Words, the absorptionof gamma rays depends only on the number of atoms per unit volume and itremains unchanged as long as the number of atoms remains the same,regardless of the nature of the composition, i. e., whether it is in theform of a mixture, solution etc.

It will be clear from the above that once the measurements are obtainedfor each substance separatel it will thereafter be necessary merely totake a single reading on any mixture or solution of these substances andfrom that reading the proportion or ratio of the substances can bequickly determined. If desired, a curve can be prepared either for thetwo substances separately or =for known ratios of the two substances,and then the ratio of the unknown composition read directly from thecurve. While the container l has been described as a vessel, it iscontemplated that it may be a pipe or conduit through which thecomposition i2 is ilowing. The pipe should be full so that the length ofthe path of the radiation beam through the composition will not vary.

In Figure 2 the invention is illustrated as applied to the determinationof the ratio of the acid catalyst to the hydrocarbons in the emulsionflowing from a contactor of the Stratco type in an alkylation system.The contactor is represented at 32 into which the isoparannichydrocarbons isobutane and butylene enter through the pipe 34. The freshacid-catalyst enters the contact-or through the pipes 36 and 38 and amotor 4Q yserves to drive an agitator, not shown, so as to emulsify theacid and hydrocarbons. The

emulsion is drawn from the upper portion of the contactor 32 through thepipe 42 and is passed to a separator 44. Part of the acid settling inthe separator may be recycled by means of the pump 49 through the pipe38 into the contactor. The pipe d2 is illustrated as having a shortvertical section l8 and on the opposite sides of this section are placedthe housing I4 containing the source of radiation and the housing 24containing the radiation detector. The output of the detector'passes tothe ampliner 28 and then to .the meter 3S as has been describedhereinbefore. By placing the source and the detector at opposite sidesof a vertical pipe one is assured that the pipe will remain full of theemulsion. Assuming that intensity measurements have been made of theacid alone and of the hydrocarbons alone when occupying the pipe section48, or that the instrument 3B has been calibrated in any other -suitablemanner it is then merely necessary to observe-or record the reading ofthe meter 30 to determine the proportions or the ratio of the acid andthe hydrocarbons when the emulsion is passing through the pipe section48.

The greater the length of the path of the radiation through thecomposition, the more accurate will be the measurements. Thus, if it isdesired to measure density variations of the order of, say, plus orminus 0.5 B.,in the emulsion flowing through the pipe 48 (Fig. 2), thehousing 24 can be raised or lowered on the pipe 48 so that the path ofthe beam will be suiciently long to provide this accuracy. In Figure 4is an enlarged section of a pipe which may, for instance, be the pipe 48of Figure 2 with the housing I4 containing the source positioned againstthe outer surface of the pipe and the housing 24 containing a detector2B positioned adjacent the. opposite side of the pipe but in a lowerposition with respect to the housing I4. .The path of the beam 22 istherefore increased and greater accuracy will be attained. The sourcemust, of course, have sufficient strength to transmit radiation .throughthe desired path 22 to actuate the detector 2B.

Figure 5 is a sectional plan view showing a modification in which ahousing I4a containing a source of radiation is mounted on the exteriorsurface of a vessel 32a, which may be, for instance, the contactor 32 ofFigure 2. Also disposed adjacent the exterior of the vessel across,-

but not necessarily exactly opposite thehousing Ma, is a housing 24acontaining a radiation detector 26a. The housing 24 is positioned withrespect to the housing l4a so that the radiation beam 22a within theemulsion will be long enough to provide measurements of the desiredaccuracy. In this manner the acid-hydrocarbon ratio of the emulsion 32acan be measured while the emulsion is still being circulated within thevessel.

Although the invention has been described as a method of measuring ordetermining ratios of substances in a composition, it is contemplatedthat these determinations can be used in connection with control inmanufacturing processes. As shown in Figure 5, the vessel 3Mr isprovided with two intake pipes or conduits 50 and 52, one for each ofthe substances to be treated within the vessel. The conduit 52 isprovided with a valve 54 actuable by suitable means such as a solenoidillustrated diagrammatically at 56. The output of the detector 26a isconnected to an amplifier 28a the output of which in turn is led to arelay 58.` The relay is connected to the solenoid 5t and is adapted inany well known manner to connect a. source of electric current 60 to thesolenoid when the relay is actuated by a predetermined increase ordecrease in the output of the amplifier 28a, Thus, assuming for examplethat isobutanebutylene enters the vessel 32a through the pipe 50 andthat the acid catalyst enters through the pipe 52, the apparatus shownin Figure 5 can be easily adjusted to maintain a desired ratio betweenthese substances in the emulsion within the vessel 32a. In case theratio should change more than an allowable amount, the response of thedetector 26a will change and the amplifier output will cause the relay58 to operate to actuate the solenoid 56 to open or close the valve 54,as the case may be, to control the amount of acid flowing into thevessel 32a.

The method is applicable in many other processes such as in continuousgrease manufacture to assure uniformity of batches, in determining theextent of polymerization in rubber manufacture, the extent of crackingand the extent of dehydrogenation in dehydro operations, and in thecontrol of fractionation operations, particularly those applied to theseparation of material in high degree of purity. The foregoing are byway of example only.

From the principles of the invention which have been described in theforegoing paragraphs` it will also be observed that since the intensityof the radiation beam passing through acomposition Varies with thedensity of that composition and since the density will vary with changesin temperature in the composition, the invention is also applicable inthe determining or measuring of temperature. Thus, with reference againto Figure 2, if the meter Seis calibrated in temperature and thetemperature of the emulsion passing through thev pipe section 48changes, the density of the emulsion will change accordingly and themeter 30 will show a different reading, indicating the new temper ature.Thus without the use of thermometers, thermocouples and the like, andwithout the necessity of access to the interior of the pipev section 43,indications or a record may be had of these temperature variations.There is usually a lag in the action of most temperature sensitivedevices such as thermocouples and the like but with the present methodthe meter 38 will respond substantially instantaneously to variations indensity of the composition withinthe pipe 48, and thus to variations inten1per,`

ature.

While the source le has been described as radium and the radiation beamas comprising gamma rays, it is to be understood that other types ofradiation can be used. For instance, neutrons emitted from a mixture ofradium and beryllium could be utilized, the detector 28 in such a casecomprising preferably an ionization chamber or a proportional counter.Likewise, in certain instances an artificially radioactive source may beadvantageous. Where penetrative radiation is referred to in the claims,it is contemplated that any of these radiations or others, such as forexample, X-rays, alpha rays, electrons and protons can be used.

It is to be understood that in the claims which follow, althoughreference may be made to a specific form of composition such as amixture, it is intended that all other forms 0f composition are to beincluded within the meaning of this term, such as solutions, emulsions,suspensions, dispersions, chemical combinations and the like.

Obviously many other modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, but only such limitations should be imposed as areindicated in the appended claims.

Iclaim:

1. The method of determining the proportions of two substances in amixture which comprises transmitting a beam of gamma rays through saidmixture over a predetermined path, transmitting said beam throughmixtures of said substances wherein the proportions of the substancesare known while maintaining the length of the path the same as for saidfirst transmission, measuring the intensities of said beam after beingtransmitted through said unknown mixture and said known mixtures, andfrom a comparison of the measurements so obtained calculating theproportions of the substances in the unknown mixture.

2. The method of determining the proportions of two substances in acomposition flowing through an opaque pipe which comprises transmittingsubstantially laterally through said pipe a beam of gamma rays when thepipe is conducting a composition of said substances and when aguacate;

the; pipel contains: each` substance: separateLY;. observing theintensities of the. beam after it? has; traversed the pipe, andt fromthev measure-y ments so.v obtained calculating. said; proportions.

3: The methodof. determining the. ratio of two" substances in acomposition: which: comprises. transmitting aY beam: ci gamma raysthrough.

said composition andl through other: composi-v tions of thesamesubstancesv wherein the ratio oi the' substances is know-n; whilemaintaining.'

constant. the lengthsV of the paths of: said beam through. theA knownand unknown compositions, measuring the intensities of ther radiation`after passing: through. said compositions',y and from said;measurements` calculating. the*l proportions ci?Y the substances in thefirst mentioned composition.`

4'. The methody of deter-mining the proportions of two'- substances in amixture in an opaque containerv which. comprises transmitting through.

said container andV said substances a beam of gamma.v rays. repeatingthisv operation when the container holds; mixtures of., saidf substancesinknown' proportions; observing the intensities of the beam. during eachtransmission,4 and.v from.

CII

the'k measurements-1 so obtainem. calculating said proportions;

GERHARD HERZOG.

REFERENCES CITED The'- following references are of' record in theA leofthisV patent:

UNITEDV STATES` PATENTS OTHER REFERENCES X-Rays and Electrons, Compton,published byl van nostrana o0., New York, N. Y. 1926),

Infra-Red' Spectroscopy, Barnes et al., published by Reinhold'Publishing Co. (1944)', New .York,iNl.,Y.

1. THE METHOD OF DETERMINING THE PROPORTIONS OF TWO SUBSTANCES IN AMIXTURE WHICH COMPRISES TRANSMITTING A BEAM OF GAMMA RAYS THROUGH SAIDMIXTURE OVER A PREDETERMINED PATH, TRANSMITTING SAID BEAM THROUGHMIXTURES OF SAID SUBSTANCES WHEREIN THE PROPORTIONS OF THE SUBSTANCESARE KNOWN WHILE MAINTAINING THE LENGTH OF THE PATH THE SAME AS FOR SAIDFIRST TRANSMISSION, MEASURING THE INTENSITIES OF SAID BEAM AFTER BEINGTRANSMITTED THROUGH SAID UNKNOWN MIXTURE AND SAID KNOWN MIXTURES, ANDFROM A COMPARSION OF THE MEASUREMENTS SO OBTAINED CALCULATING THEPROPORTIONS OF THE SUBSTANCES IN THE UNKNOWN MIXTURE.